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Community and Q&A

What tape to use on my basement interior polyiso?

tydotten | Posted in Energy Efficiency and Durability on

I am choosing to insulate my basement walls with 2″ of Polyiso and am curious: what I should use to seal the seams? Will regular UL Listed 181B metal duct tape work, or is there a better option?


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  1. tydotten | | #1

    Also, any ideas about what kind of adhesive to use directly against the concrete?


  2. NBABUCKS1 | | #2

    is it foil faced? what is on the facing?

  3. GBA Editor
    Martin Holladay | | #3

    If the polyiso is foil-faced, housewrap tape is a good choice. More information here: Backyard Tape Test.

  4. tydotten | | #4

    Perfect, thanks Martin. It is foil faced (RMax). Is there any real advantage to one adhesive over others?

  5. GBA Editor
    Martin Holladay | | #5

    Clearly, a tenacious tape is preferable to one that isn't very sticky.

  6. tydotten | | #6

    Indeed. I wasn't clear enough in my question though.

    I am looking to adhere the RMax directly to the concrete wall in my basement. Some kind of low VOC adhesive would be preferred, but I was curious if anyone had a good construction adhesive for this application.


  7. GBA Editor
    Martin Holladay | | #7

    As far as I know, almost any construction adhesive is compatible with the foil facing on polyiso.

    Use an adequate amount of adhesive, and apply pressure (using scrap pieces of plywood or OSB held in place with long 2x4s or 2x6s extending from the scraps to a solid location -- jam the 2x4s in place to apply pressure) for several hours.

  8. albertrooks | | #8


    Siga Twinet will work well in this application. It's an extremely tenacious double stick tape that's made to hang interior membranes onto framing. Since your bonding to concrete, I'd prime the wall with Siga Dockskin primer.

    I'm suggesting this because you would not have to keep pressure on the PI while the adhesive dries. Just press the PI onto the wall and it's done. It works because the layer of adhesive is really thick. Lots to stick with!

    I've done this with our Cork insulation and when I had to take the test wall down a couple weeks later, it ripped the cork apart rather than break the bond. On a primed concrete wall, the results will be the same. (the primer only goes where you put the tape.)

    Here is a rough video of the cork experiment:

    Here is the tape in our store.

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